In a conventional vehicle having an internal combustion engine for providing drive torque for driving the vehicle forward, as a rule auxiliary assemblies of the vehicle, such as air conditioning compressors, water and fuel pumps, are driven directly by the internal combustion engine, i.e., are supplied with a torque. In electric and hybrid vehicles, a problem occurs such that when the vehicle is at a standstill, no drive moment which might drive the auxiliary assemblies is provided by the electric motor which acts as drive unit.
In order to solve this problem, instead of rotationally driven auxiliary assemblies, electrically operated auxiliary assemblies can be used which take the energy which is necessary for their operation from a battery of the vehicle. Electrically operated auxiliary assemblies of this type, however, are considerably more expensive than conventional auxiliary assemblies with rotary drive.